In mailing systems of the type described in application No. 476,618 filed June 5, 1974, now U.S. Pat. No. 3,877,531; a reliable feed and stacking apparatus is required, that will insure a proper feeding of individual pieces of mail. Too often, more than one piece of mail will be fed into a mailing apparatus, usually causing a jamming in the transporting of the letters. A double feed of envelopes not only causes jamming, but requires operator attention to separate the doubles and reprocess the mail through the mail system.
An analysis of the problem has shown that doubles often occur as a result of frictional forces between the envelopes. In other words, when one envelope is discharged from the feed deck, an adjacent envelope is often pulled along with this envelope, by virtue of the friction existing between these contiguous pieces of mail.
The present inventive feed-in stacking apparatus is designed to reduce the probabilities of incurring a double feed.
Another problem common to feed-in stacking devices, is the maintenance of a constant magnitude of feed force despite the size of the stack. The present invention has means for providing a substantially constant feed force magnitude upon the stack of mail regardless of the stack size.